Against a backdrop of rising demands of environment protectionism, the development of electric vehicles (EV), hybrid electric vehicles (HEV), and fuel cell vehicles (FCV) has been flourishing in recent years. What is attracting the attention of the market as a potential power source for driving the motors used on those vehicles is the rechargeable bipolar battery.
The electrode of the bipolar battery consists of a negative electrode formed on one side and a positive electrode formed on the other side of the collector. The collector is provided with a sealing part that prevents the leakage and evaporation of the electrolyte that is caused to permeate into the positive and negative electrodes. The sealing part is formed by overlaying the collector with a hot-melt type sealing layer comprising a plastic material and adhering them together by applying heat.
The collector used on the bipolar battery is composed of a material selected from various materials from the standpoint of improving the performance of the bipolar battery. A collector composed of a polymer material in lieu of a conventional metal foil has been proposed in order to obtain a lightweight collector (see Patent Document 1). Patent Document 1 discloses the use of a thermosetting resin as such a polymer material. In the disclosure, the sealing part is formed by using a hot-melt type thermoplastic resin as the sealing layer and adhering it to the collector by means of a hot press.